Generally, a jack is convenient to carry owing to its small volume and frequently used to lift a vehicle body itself for changing a tire or repairing the vehicle. A lifter is used to lift rather bigger work piece such as from a compact car till 8-ton dump, so having large volume and heavy weight not to be carried. The lifter is usually used in a maintenance station.
Such a conventional hydraulic jack or lifter has an advantage of easily safely lifting a large object with a relative lower force. The conventional hydraulic jack or lifter needs to pump oil by reciprocate a jack lever or handle like levering in order to lift a work piece to a desired height. In other words, there is an inconvenience to manipulate the handle repeatedly till contacting to a bottom of the vehicle body.
The conventional hydraulic jack or lifter is also unhandy since it requires so much strength to manipulate the lever due to load of a lifted object. If the jack or lifter is moved utmost, the jack does not move upward and the jack lever is also not manipulated any more. In addition, excessive load or hydraulic pressure inside the jack or lifter may cause breakage of a sealing such as O-ring or gasket, so leakage of the oil.